by Rebecca Wilkins

March 16, 2016

We’ve had a lot of questions about batteries so we wrote up a short, simple explanation on how batteries work.

How Batteries Work

Batteries have three parts: an anode (negative side), a cathode (positive side), and the electrolyte.

The cathode and anode are attached to conductive material in an electrical circuit. The chemical reactions in the battery cause a build-up of electrons at the anode. The electrolyte allows a flow of charge between the anode and cathode, completing the circuit between the two opposing materials.

You can think of a battery as a small power plant that converts a chemical reaction into electrical energy. Various dry cell (or alkaline) batteries can differ in several ways, but they all have the same basic components.


Two main types of batteries are primary cell and secondary cell.

Types of Primary Cell Batteries: Zinc-carbon cells, Alkaline batteries, Lithium batteries, Silver oxide batteries, and Mercury batteries.

Types of Secondary Cell Batteries: Lithium ion batteries, Nickel-cadmium batteries, and Nickel metal hydride batteries.

The two main types of cells are wet cell and dry cell.

A wet cell battery has a liquid electrolyte.

A dry cell uses a paste electrolyte, with only enough moisture to allow current to flow. 

The most common battery sizes are AAA, AA, C, D. They come in teeny tiny sizes for electronics and large sizes for vehicles and buildings.

13 Facts About Batteries

1. You can make batteries with fruits and vegetables!

2. You can make a battery with a jar of water. (The word "battery" was used by Ben Franklin to describe multiple Leyden jars.)

3. As far as we know, Italian professor Alessandro Volta made the first battery in 1798.

4. Americans purchase nearly 3 billion batteries every year!

5. You can buy a battery to power your house! Tesla’s super cool Powerwall is a rechargeable lithium-ion battery designed to store energy at a residential level for self-consumption of solar power generation, load shifting, and backup power.

6. Dead batteries are the number one reason for road service calls in the U.S.

7. All batteries die eventually, but some are rechargeable.

8. Rechargeable batteries work by reversing the chemical reaction using electrical energy. For instance, instead of electrons flowing from negative to positive, they are made to flow in the opposite direction. Eventually, even rechargeable batteries lose their storage capacity and it can’t be restored.

9. Rechargeable batteries have a lower capacity than disposable alkaline batteries. The lower the storage capacity of a battery, the shorter amount of time it can power something before it needs to be recharged or tossed.

10. You can slightly extend battery life by storing them in cool temperatures, such as in the fridge or freezer. Hot temperatures zap the battery’s capacity, so keeping them in a cool place can keep this from happening.

11. You can test to see if your batteries are dead by dropping them on a hard surface.

12. You can recycle your batteries for free!

13. Sunday, March 13th is Check your Batteries Day! Even if you miss the day, it’s a good idea to check the batteries to make sure they're not dead.

Comment below and let us know what else you want to know about batteries or circuits!

About the author 

Rebecca Wilkins

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